I just want a small box with an LCD that will tell me how many minutes I have spent on long distance for the month, show how much it has cost, and shut me off until the following month when I've reached a preset limit. I'm afraid to actually create and sell this for fear of having an untimely accident.

This isn't quite what you want, but some long distance providers offer instant Web-based account tracking, so you could at least check it periodically. You can also get prepaid long-distance accounts to prevent yourself from overspending. I'm not sure if these features are available on a "primary" long-distance carrier, or only on "calling card" systems like BigZoo...

I think that your collective suggestions are spot-on. A calling card seems to be the simplest solution, and probably the one we will adapt. I attempted to purchase a version of the above, but it turned out to be a surplus three pound beige box called the "telecoster" that required the user to push a start and stop button each time they initiated a LD call. I know that many cellular phones contain this. Perhaps a cellular that acts as a cordless locally would also work. Many thanks.